Develop microsphere and microencapsulation formulations and procedures to stabilize NCI-provided synthetic retinoids while maintaining good bioavailability. Determine the stability of the neat and encapsulated retinoids at 23, 37, and 45 C under various conditions. Perform bioavailability studies on the near and selected samples of the encapsulated retinoids using rats as the animal model to demonstrate good bioavailability. Encapsulate, prove bioavailability, and furnish at least thirty experimental retinoids of either kinogram quantities per retinoid or 10-50 grams per retinoid.